Grinder



Nov. 9, 1937. c. AMMQN 2,098,480

GRINDER Filed Oct. 14, 1935 2 Shets-Sheet' l gvwcm v C. D. Ammon C. D. AMMON Nov. 9, 1937.

GRINDER Filed Oct. 14, 1935 2 Sheets-Sheet 2 Fig.2

gn/ucnioc C. D. Ammon Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE Claims.

My invention relates to mills and especially to the mills of the type known as hammer mills in which the hammers are rotated at high velocities about an axis to crush the material partly by the 5 impact of the hammers against the material and partly by the impact of the material as it is forcibly hurled against stationary anvils.

The primary object of the invention is the provision of a mill which will not clog, particularly when the velocity of the hammers slows up.

Another object of the invention is the provision of a rearrangement of the parts of a hammer mill for lifting the ground material with a greatly reduced expenditure of energy whereby if) the ground material may be handled in the mill at much lower velocities.

Another object of the invention is the provision of a baffle which may be adjusted relative to the mouth of the mill for reducing the tendency of q the mill to choke at that point and resulting in a more uniform feeding of the material into the mill.

Another object of the invention is the provision of an improved device for facilitating the insertion and removal of screens to make it possible to insert or to remove the screens much more quickly and easily than has heretofore been possible.

Still another object of the invention is the provision of a novel form of screen clamp which not only provides means for applying powerful pressure to seat the screen in place but which applies opposing tangential thrusts against the opposite edges of the screen to buckle the screen into its normal position against abutments which prevent excessive buckling of the screen from the material in the grinder chamber of the mill.

Having in view these objects and others which will be pointed out in the following description, I will now refer to the drawings, in which Figure 1 is a view in perspective of the entire mill, parts being broken away to disclose interior construction.

Figure 2 is a view in vertical section through the grinding chamber.

Figure 3 is a view in perspective of a detail for adjusting the anvil.

Figure 4 is a View in vertical transverse Section of the mill showing particularly the grinder and fan chambers in their relation to each other and showing also the shaft which carries both the hammer reel and the fans.

Figure 5 is a sectional view of a fragment of the mill showing particularly the screen clamp 55 ing mechanism.

The mill or grinding chamber includes a front wall 10, a top wall II, a rear wall l2 and side walls l3 and I4. The rear wall l2 as well as the side walls I3 and I4 merge into a conduit l5 having a generally horizontal direction. 5

Secured to the mill or grinding chamber of the mill is a fan chamber l6 containing the fan IT. This fan is secured to a shaft which also carries the hammers l8 and which has its bearings in the side walls l3 and H. The fan chaml0 ber I6 is provided with a top opening l9 through which the ground material is driven by the blast of air. The opening I9 is so arranged that a discharge pipe may be secured thereto for delivering the ground material at any desired point. The conduit l5 enters the fan chamber l6 through its outer side wall.

The screen is positioned in the rear of the hammer reel 2| and forward of the rear wall I! and centrally of or near the level of the hammer reel. This arrangement is important in reducing to a minimum the lift of the ground material to the blower unit, thus preventing the choking of the passageway when the fan is slowing down. The mill casing is provided with a door 22 for giving access to the screen 20. This screen abuts against the edge of the bottom wall of the grinder chamber under the anvil 23 which securely holds the lower portion of the screen in position. The closing ofthe door 22 maintains the screen in firm position but this screen may be readily removed and replaced whenever desired by first opening the door 22, this being subsequently described more fully. The hammer mill casing is also provided with a funnel inlet 24 in its forward wall ill.

The material entering through the funnel 24 is acted upon by the hammers l8 and the ground material is forced through the apertures of the screen 20. These hammers due to their rapid rotation develop great centrifugal force and set up a powerful current of air which forces the ground material against the screen but this action is intensified by the suction of the fan I! which. causes a partial vacuum in the rear of the screen 20. The material thus ground is discharged through the opening IS. The ground material must pass through the conduit l5.which is horizontally positioned so that it is not lifted in its passage from the screen 20 to the fan II. This is of importance since the slowing down of the fan will otherwise result in the choking of the mill.

In Figures 2 and 3, I show additional mechanism for preventing the choking of the mill.

CAD

The material is ground not only by the hammers I! but it is hurled against a baiile 21 which further reduces the material. This ballle 2'! lies approximately in the tangent of the circle of rotation of the hammers, the tangent passing through the funnel 24. Stationary anvils similar to the baille 21 are in common occurrence in hammer mills but a fixed position for the initial baiiie is undesirable in mills which are designed for grinding feeds all the way from grains to damp hay. When the baiiie is in fixed position it may func-- tion perfectly for one kind of material but the mill may clog up when another kind of material is used due to the fact that the battle is in the wrong position relative to the'feed opening when the mill is used for another kind of material. I therefore provide an adjustment of the baffle relative to the opening as shown in Figures 2 and 3.

Secured to the side wall I is an L-shaped bracket 23 which is arcuate and concentric with the shaft of the mill. The side wall ll of the mill is provided with an arcuate slot 29 immediately above the upper edge of the bracket 23, the slot 29 being adapted to receive the end of the bailie 21 as shown in Figure 3. This bafile 21 not only passes through the slot 29 but it is adjustable therein by movement back and forth in the slot 29. The thrust of the material against the anvil 21 is rearward. In the rear of the anvil and at the rear end of the bracket 28 is an L-shaped bracket 30 having a screw threaded aperture for the reception of a set screw 3!, the end of the set screw bearing against the rear edge of the anvil 21. The anvil 21 may thus be moved forwardly by means of the set screw 3i. If it is desired to move the anvil 21 rearwardly it is only necessary to turn the screw in the reverse direction so that the impact of the material against the forward edge of the baffle 21 will cause the baille to move rearwardly until it contacts with the end of the set screw 3i.

As best shown in Figure 2, the screen 20 is in the rear end of the grinder chamber and the opening for the screen is relatively large. The lower and upper edges 0! the screen lie substantially in the projected lower and upper horizontal tangential planes of the cylinder of rotation of the hammers. The anvil 23 is positioned to overlie the lower edge of the screen opening so that the screen 20 may be inserted underneath the anvil 23 to form a continuation of the lower wall of the grinder chamber. A screen holder frame consisting of two or more arcuate memhers is employed to bear against the rear surface of the screen 20 at its edges. These arcuate members are each preferably in the form of a plurality of sections 32 and 33 but their number may be either increased or decreased. The section 32 is secured to a rod 34 which may serve as a pivot if only one section is employed or if otherwise desired when more than one section is employed. The section 32 may also be an arcuate rib projecting inwardly from a side wall of the grinder chamber and integral therewith. The sections 32 and 33 are secured to the rod 35 which functions as a pivot for the section 33. The arm 36 is eccentrically pivoted to the upper end of the section 33. On the under side of the arm 36 is a bar 31 which projects slightly beyond the edge of the arm 36. When the screen is secured in place the arm 36 abuts squarely against the upper edge of the screen so that the thrust of the arm 36 on the screen 20 is tangential and toward its lower edge.

A bar 33 is secured to the top wall ll of the grinder chamber, the bar being underneath the pivot of the door 22 and projecting slightly beyond the edge of the door. In theFigure 2 position the arm 36 has its forward edge abutting against the rear edge of the top wall Ii.

The importance of this structure residesin the ease with which screens may be withdrawn and replaced and still more in the fact that the screens are very firmly held in place without direct clamping action. The only clamping action is at the upper and lower edges of the arcuate screen but even this is relatively light because the dependence is placed mainly on the tangential thrust against the screen at the upper and lower edges. The action of the material in the grinder chamber is such that the thrust against the screen is tangential and in an upward direction.

The screen is in effect buckled into its normal shape by reason of the pressures exerted at the upper and lower edges of the screen. The arcuate members 32 and 33 serve merely to prevent excessive buckling. When it is desired to remove a screen it is only necessary to first lift the lid 22 and then to grasp the arm 36 and to lift it on its pivot. The pivoted. arcuate section may then be lifted to entirely free the screen so that the screen may be lifted out. Another screen may then be inserted and the arcuate members may be swung forwardly on their pivots so that the screen may be clamped by pressing down on the arm 36. This engages the rear edge of the arm 36 with the top edge of the screen so that downward movement of the arm 36 will exert a powerful pressure to fully seat the lower edge of the screen. The closing of the door 22 will then still further depress the arm 36 and it will firmly rea tain the arm 36 in its closed position. The door 22 may be latched in closed position by means of any desirable latching mechanism such as the thumb nuts 39. The buckling of the screen against the arcuate ribs entirely eliminates the vibration and chattering which is so troublesome in all other hammer mills and in fact in all other mills operating at high speeds.

In many of the prior mills the body of the mill is divided through the center, one part opening up to permit the removal of the screen. It is readily apparent, however, that this greatly weakens the structure of the mill. In other mills various doors are provided for giving access to the screen but none of these effectively seals the open ing against the expulsion of ground feed around the door nor provides convenient means for looking the screens tightly in position.

Having thus described my invention in such full, clear, and exact terms that its construction and operation will be readily understood by others skilled in the art to which it pertains, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A hammer mill including a casing and a hammer reel therein, a hinged door in the rear portion of the top wall of said casing, a grinder chamber surrounding said hammer reel and having a floor in the form of a cylindrical arc, an arcuate screen abutting at its lower edge against the rear edge of said floor in arcuate continuation therewith, a pair of pivoted arcuate abutments for engaging the lateral edges of said screen, and a lever at the upper extremities of said abutments, said lever being below the arc of said abutments and having a lower edge for pressing contact with the upper edge of said screen, the free edge of said lever being adapted to abut against the upper wall of said casing beneath the hinge of said door whereby the closaoeaeeo (If;

ing of said. door will buckle said screen into innmate contact with said abutments.

2. In" a hammer mill, a casing having a grinding chamber therein with a screen opening in-its back wall, a screen for said opening, a frame hinged to the lower wall of said chamber and extending to the top wall thereof for engaging the screen, a lip hinged to the free end of said frame and having an eccentric heel part for engagement with the upper edge of the screen to compress the same into the frame, and a hinged cover mounted on the casing over said frame and adapted when closed to engage the upper end of the frame for binding the lip against the screen and holding the frame in place.

3. In a hammer mill, a casing having a grinding chamber therein, a hammer reel in the chamber of the casing, a screen disposed in the rear wall of the chamber within the casing, a screen holding frame in the casing extending from the bottom wall of the chamber and having its upper part terminating adjacent the top of the casing, said frame adapted to engage the marginal lateral edges 01' the screen to hold the same in place, a lip hinged eccentrlcally to the upper end of the frame and having a heel portion to engage the screen, a ledge carried by the casing beneath the top wall thereof to receive said lip, and a cover in the top wall of the casing adapted to be closed thereon and engage the upper end of the frame to clamp the same in place with the lip on said ledge and bind the heel of the lip against the upper edge of the screen and conform the latter to the frame.

4:. In a hammer mill, a casing having a grinding chamber therein, a hammer reel in the chamber of the casing, a screen disposed in the rear wall of the chamber within the casing, a screen holding frame in the casing extending from the bottom wall of the chamber and having its upper part terminating adjacent the top of the casing, said frame adapted to engage the marginal lateral edges of the screen to hold the same in place, a lip hinged eccentrically to the upper end of the frame and having a heel portion to engage the screen and a cover in the top wall of the casing adapted to be closed thereon and engage the upper end of the frame to clamp the same in place and bind the heel of the lip against the upper edge of the screen and conform the latter to the frame.

5. In a hammer mill, a main casing, a fan casing mounted on one side of the main casing, a horizontal shaft disposed axially in the main and fan casings, a hammer reel on the shaft in the main casing, a fan on the shaft in the fan casing, an inlet extending downwardly in the front side of the casing at substantially a tangent to the bottom wall thereof beneath the hammer reel, an arcuate screen extending from the rear end of the bottom wall in upright position in the rear side of the casing to receive therethrough ground material thrown ofi by the hammer reel for accumulation in the rear bottom portion of the casing, said casing having a collecting sump at its lower rear portion the lower wall of which extends outwardly from the screen and generally horizontally relative to the bottom wall of the casing, and a substantially horizontally disposed conduit extending from said collecting sump at said lower wall around the exterior of the main casing to said fan casing, whereby ground material tending to choke said conduit upon overloading of the main casing may gravitate along the bottom of the conduit without entirely closing the same so that the continuous draft of air may gradually absorb the overload of ground material and prevent the choking of the mill.

CHARLES D. AMMON. 

